1. Field of the Invention
The present invention relates to suspensions of particles containing transition metal compounds in oils. It also relates to processes for the polymerization of alpha-olefins carried out in the presence of these suspensions.
2. Background of the Related Art
Many recent processes for the manufacture of particles containing solid transition metal compounds (titanium halides, supported or otherwise, etc.), which can be employed for the polymerization of olefins give rise to fine powders of very uniform morphology (microspheres of very narrow particle size distribution). Such morphology offers advantages, not only because the transport and the storage of these particles are made easier, but also because this morphology facilitates the direction and the control of the polymerizations carried out in their presence.
In practice, hitherto, these particles have been handled, packaged and employed either in the form of suspensions in inert hydrocarbon diluents, preferably the diluents which may be employed for the subsequent polymerization, or in the form of dry particles.
It is true that in patent FR-A-1,433,944 (The Goodyear Tire & Rubber Company) there is also a description of "suspensoid" compositions of solid transition metal salts, which can be employed as catalyst components for stereospecific polymerization of olefins, in "semisolid" or viscous hydrocarbons which protect them from certain contaminating factors such as air and water in the course of their handling, packaging, transport and use. These compositions prevent the deposition of certain constituents of the catalyst, provide a more homogeneous system and simplify the measuring out of the constituents. In practice however, the dimensions of the particles of these salts are relatively large (between 175 and 74 .mu.m); according to the examples, suspensions of titanium tetraiodide crystals in liquid paraffin are manufactured. The patent provides no indication as to the particle size distribution of the particles.